1. Field of the Invention
This invention relates to mechanical excavators of the type comprising a boom of variable length, mounted on a support part for up and down movement about a horizontal axis, a dipper arm pivotally connected to the boom at or near the outer end thereof and the dipper arm carrying at one of its ends an excavating tool there being fluid operated means to cause pivotal movement of the boom relative to the support part and of the dipper arm relative to the boom. Such an excavator will be referred to hereinafter as "of the type described".
An excavator of the type described may be mounted on a sub-frame which is mounted on a ground engaging propulsion means by a turntable assembly whereby the sub-frame and excavator mounted thereon can rotate relative to the propulsion means about a vertical axis. The sub-frame may also carry the operators cab, fluid control means and an engine for providing power for driving the machine and the ground engaging propulsion means may comprise a pair of endless tracks or alternatively may comprise a wheeled propulsion means.
Alternatively an excavator of the type described may be mounted at the rear of a tractor the support part comprising a frame mounted on the rear of the tractor or alternatively the support part may comprise an integral part of the tractor.
An object of the invention is to provide a new and improved excavator of the type described.